Re: [PATCH v3] nvmem: u-boot-env: align endianness of crc32 values

From: Christian Lamparter
Date: Fri Feb 17 2023 - 12:30:39 EST


On 2/13/23 14:37, Rafał Miłecki wrote:
On 2023-02-13 14:23, INAGAKI Hiroshi wrote:
This patch fixes crc32 error on Big-Endianness system by conversion of
calculated crc32 value.

Little-Endianness system:

  obtained crc32: Little
calculated crc32: Little

Big-Endianness system:

  obtained crc32: Little
calculated crc32: Big

log (APRESIA ApresiaLightGS120GT-SS, RTL8382M, Big-Endianness):

[    8.570000] u_boot_env
18001200.spi:flash@0:partitions:partition@c0000: Invalid calculated
CRC32: 0x88cd6f09 (expected: 0x096fcd88)
[    8.580000] u_boot_env: probe of
18001200.spi:flash@0:partitions:partition@c0000 failed with error -22

Fixes: f955dc144506 ("nvmem: add driver handling U-Boot environment variables")

Signed-off-by: INAGAKI Hiroshi <musashino.open@xxxxxxxxx>
---
v2 -> v3

- fix sparse warning by using __le32 type and cpu_to_le32
- fix character length of the short commit hash in "Fixes:" tag

v1 -> v2

- wrong fix for sparse warning due to misunderstanding
- add missing "Fixes:" tag

 drivers/nvmem/u-boot-env.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
index 29b1d87a3c51..164bb04dfc3b 100644
--- a/drivers/nvmem/u-boot-env.c
+++ b/drivers/nvmem/u-boot-env.c
@@ -117,8 +117,8 @@ static int u_boot_env_parse(struct u_boot_env *priv)
     size_t crc32_offset;
     size_t data_offset;
     size_t data_len;
-    uint32_t crc32;
-    uint32_t calc;
+    __le32 crc32;
+    __le32 calc;
     size_t bytes;
     uint8_t *buf;
     int err;

This looks counter-intuitive to me, to store values on host system in
specified endianness. I'd say we should use __le32 type only to
represent numbers in device stored data (e.g. structs as processed by
device).

My suggesion: leave uint32_t for local variables and use le32_to_cpu().

Hmm, this is strange. The kernel's u-boot-env driver works without any
additional changes in the le<->be department on the Big-Endian
PowerPC APM82181 WD MyBook Live NAS.

Is there something odd going on with the WD MyBook Live, or is it
the APRESIA ApresiaLightGS120GT-SS that is special?

Regards,
Christian